1. Field of the Invention
The present general inventive concept relates to an apparatus and a method to perform sound processing in a virtual reality system, and more particularly to a sound processing apparatus and a sound processing method that can process sound in a focus area of a virtual reality system differently from sound in an un-focus area.
2. Description of the Related Art
The rising popularity of simulators that enable users to feel like they are experiencing an actual life in a three dimensional virtual reality has led to the development of virtual reality systems. Virtual reality systems may be used to provide a high degree of realism in an electronically-manufactured environment, such as in a virtual reality game or a 3D game.
Virtual reality systems allow users to feel various manufactured sensory inputs (including visual sense, auditory sense, and tactile sense) in a virtually formed space. The sensory inputs may replicate sensory experiences of the real world with varying degrees of realism. For example, in a virtual reality game, life-like images and sounds may be generated, but a game joystick or controller may only roughly imitate a real-life sensation of contact by vibrating. An image of a virtual reality system may be three-dimensionally realized by using a monitor, a Head Mounted Display (HMD), a television, a projector, or any other visual display device. Further, the sound of the virtual reality system may use a localization technique capable of expressing the virtual location. Sound of a virtual reality system may be generated by speakers, a headset, or any other audio device.
According to a sound processing method in the virtual reality system as described above, it is possible to make a change in the sound by modeling the path and change of sound according to relative locations of a sound-generating object, locations of surrounding things, and direction of sound propagation, to give the sense of reality to the sound. Further, to express directionality, the paths of the sound reaching listener's ears, which determine the direction of sound in view of the listener, may be modeled by using a sound processing technique, such as a Head Related Transfer Function (HRTF), so as to determine the output sound.
When a user moves in a virtual environment, the real world is imitated as much as possible. However, in some situations it may be more convenient for a user if movement in the virtual environment does not precisely mimic the real world. For example, unlike the real world in which a user cannot avoid making a continuous movement according to the passage of time, in a virtual environment, a user can shift between virtual spaces without having to portray the passage of distance or time to travel from one space to another. An example of such a virtual reality system includes a virtual reality game, “Second Life,” developed by Linden Lab of the United States. In such a virtual reality system, when a character of a user shifts between virtual spaces, the image viewed by the user and the sound heard by the user should change according to the shift between spaces or the change of the spaces. Since the spaces between which the character shifts are different from each other, the two sounds heard in the spaces are output from different sound sources. Therefore, there may be a time delay between the sound outputs during the space shift, which may degrade the sense of reality in the sound. Therefore, a sound processing technique is needed to provide a virtual reality that can give a higher sense of realism.